Unveiling the Therapeutic Potential of Thymol from Nigella sativa L Seed: Selective Anticancer Action against Human Breast Cancer Cells (MCF-7) through Down-Regulation of Cyclin D1 and Proliferative Cell Nuclear Antigen (PCNA) Expressions

Abstract

Abstract The present study aimed to examine the antiproliferative and anticancer role of thymol by suppressing Cyclin D1 and proliferative cell nuclear antigen (PCNA) expression, which instigates the proliferation of cancer cells and prevalent overexpressed apoptotic marker gene in breast adenocarcinoma cells (MCF-7). The cytotoxic effects of thymol derived from Nigella sativa (NS) on MCF-7 cells was performed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release methods. The tested increasing concentrations (0- 1000 µM) of thymol inhibited the MCF-7 cell growth significantly. Thus, 200 µM of thymol inhibited 50% of MCF-7 cell growth, and the specific cytotoxic effect of thymol was intended to identify the anticancer mechanistic effects. Cyclin D1 and PCNA gene expression in thymol-treated and vehicle control groups MCF-7 were quantified using real-time Polymerase Chain Reaction (RT-qPCR). The results indicated that the downregulated gene expression of Cyclin D1 and PCNA relative to the vehicle control. This study shows that thymol extracted from NS had an MCF-7 specific cytotoxic effect through suppressing the expression of Cyclin D1 and PCNA. The experimental results were verified, and possible protein–ligand interactions were investigated using CB-Dock2 sever. This investigation showed that thymol could be an effective drug for MCF-7. However, further, in vivo research needs to determine its efficacy and safety in medical applications.